Pyrometer bulb



April 1961 K. .J. KNUDSEN ETAL 2,981,106

PYROMETER BULB Filed Oct. 8, 1957 INVENTORS Knud J. Knu cmwenoe I. McCQH I GEJVT Unite i PYROll/ETER BULB Knud J. Knudsen, Middlebury, and Clarence I. McCall,

Waterbury, (301111., assignors to Lewis Engineering Company, Naugatuck, Conn., a corporation of Connecticut Filed Oct. 8, 1957, Ser. No. 683,944

4 Claims. (Cl. 73-339) This invention relates to pyrorneters or high temperature, thermometers, and more particularly to the bulb structures of pyrometers. 7

With the advent of atomic reactors, nuclear equipment I and the like, existing temperature measuring and controlstrength, but to lack suflicient ease of interchangeability damage to operating personnel.

The above drawbacks and disadvantages of prior, existing pyrometer bulbs are obviated by the present invention, and one object of the invention is to provide a novel and improved pyrometer bulb adapted for immersion in rapidly flowing fluid held under high pressure, which bulb is highly resistant to vibration and failure resulting from turbulence and vibratory forces, while still retaining a rapid and desirable speed of response to temperatre variations.

Another object of the invention is to provide a novel and improved pyrometer bulb and fitting construction in accordance with the above, which is devoid to the maximum extent of fissures, crevices or pockets wherein a contaminated fluid may become lodged and remain.

Afurther object of the invention is to provide an improved pyrometer bulb and fitting structure which is highly resistant to the corrosive action of a contaminated fluid exhibiting radioactivity. I

St l further object of the present invention is to proide an mproved pyr meter bul a fitti structure as above characterized, wherein replacement of the bulb and the sensing element thereof may be effected with a maximum degree of ease and facility.

Another object of the invention is to provide an improved pyrorneter bulb and fitting assembly for incorporation in a pipe line carrying contaminated fluid, which assembly is normally leak-proof at the proper operating pressures of' the line and 'yet is adapted to permit a controlled leakage upon the, fluid pressures rising to predetermined abnormal values. I

A feature of the invention resides in the provision of a novel and improved pyrometer bulb and fitting structure having all of the above advanatges and characteristics, and which is nevertheless, relatively simple and economical in construction, and of the greatest reliability throughout an extended period of use. I

Qther features and advantages will hereinafter appear.

in the drawings accompanying this specification, similar cha eters of reference indicate corresponding parts wherever'nessible in. the several v e in which Patented Apr. 25, 1961 Figure l is an axial sectional view of an improved pyrometer bulb with associated fitting structure and rapid response sensing element made in accordance with the invention.

Figure 2 is an axial sectional view of a fluid pipe line having incorporated therein the improved pyrorneter bulb and fitting structure of Figure 1, said bulb and structure being shown in side elevation.

Figure 3 is an end elevational view of the bulb and fitting structure, looking at the connector end thereof.

Figure 4 is a fragmentary view of the outer end of the bulb and fitting structure, shown partly in elevation and partly in axial section and illustrating a modification of the invention.

Figure 5 is a fragmentary sectional view taken on line 5-5 of Figure 3, showing a part of the outer or lip portion only of the connector shell of this invention.

Figure 6 is a fragmentary sectional view showing part of the inner end portion of the connector shell,-that located opposite to the end. portion shown in Figure 5,

and showing a welding bead on said inner end portion,

provided to facilitate welding of the shell to the bulb body.

Considering first Figure 2, there is shown a pipe line 2% adapted to carry a stream of fluid such as the radioactive, contaminated cooling water of an atomic reactor. The flow of fluid in the line 20 is taken as in the direction indicated by the arrow. In one side wall, the pipe line 20 has an angularly disposed hollow projection or boss 21 provided with internal screw threads 22 for receiving an externally threaded bushing 23. The boss 21 is shown as having a sloping bore 24 intersecting the main passage of the pipe line 20 at an acute angle, illlustrated as approximately 45.

Normally, the cooling water is intended to flow in the line 2t) at a rapid rate and under considerable pressures, and such water flowing against and around any projection, as for example a pyrometer bulb disposed in the passage, will cause turbulence and eddies, and will exert periodic forces against such bulb. Consequently a tendency to vibration is set up in the bulb, and we have found that the thin-Walled slim and elongate, rapid-response bulbs heretofore available suffered mechanical failure as a consequence of vibration. Prior bulbs under test were found to readily vibrate with a frequency of approximately 1000 cycles per second, and such relatively low vibration resulted in appreciable stressing and movement of the bulb, to the extent that cracking of the bulb jacket and ultimate failure would occur.

'In accordance with the present invention there is provided, for mounting within the bushing 23, a novel'and improved bulb'structure which, while retaining the relatively thin walls necessary for rapid response of the sensing element to temperature changes, exhibits a much greater or higher natural frequency, having a resonant frequency in excess of 2000 cycles per second as compared with the 1000 cycle per second frequency of prior pyrometer bulbs. In obtaining such appreciably higher resonant frequency, the present improved bulb employs a large-diameter stem portion adjacent its' base and a novel, tapered construction between the base and tip portions, facilitating its fabrication by means of stamping or drawing operations not requiring an anneal, and also attain ing a desirable, minimum number of microcracks per square centimeter over its entire exposed surface. With a bulb structure and shape as herein provided we have found, also, that erosion and wear arelessened and held to a minimum.

Referring to Figure 1, the bulb 26 shown therein comprises an elongate, tubular and hollow body having a closed end portion 27 of cylindrical shape and of a diameter commensurate with that of thin walled, rapidresponse bulbs heretofore employed in pyrometers. The

assume I bulb 26, however, has an open end portion 218 of enlarged diameter, appreciably greater than the diameter of the portion 27. 7 Intermediate the endportions 27 and 28 the bulb body has a generally 'tapering'configuration, and

we have found it to be advantageous in making the bulb to provide a pair of tapered portions-29 and. 30 separated by anintermediate cylindricalportionfl- The end por- 7 tion 28 of enlarged diameter'closely slidably fits in the 1 bore of the bushing 23ers shown, so as to be rigidly supported thereby, and: it will be notedfrom Figure 2 that the tip portion 27 of relatively small diameter is disposed substantially whollyinthe path ofiluid flowing through the pipe line 20, whereas the tapered portion 29 and in- I termediate cylindrical portion 31'are disposed partly in I the path of the fluid, and partly'out of said path. 'The tapered portion 30 and cylindrical end portion 28 of enlarged diameter are not disposed at allin the direct path 1 of the fluid in the line20. t

Moreover, vtheextrerne tip, or extremity'of theclosed,

end portion-27 of the bulb is fabricated as indicated at 33, so as to have virtually arperfect radius, thereby to Y vlessen eddies in the fluid, flowing, through the line 20. I

1 We have found that with such a'bulb construction the I resonant frequency ofvibration is more than doubled, as 1, compared with acompletely cylindrical bulb having a diameter-commensuratefwith that: of the tippportion 27,

andthat suchdoubledfrequency may be higher than 1 "2000cyclesper second. Accordingly, the degree of: de':

, fiection of the bulb 26 is greatly lessened, so much so thatrnechanical failure due to vibratory forces and condi- 1 v tions caused bytheturbulence and pressure ofthefluid flowing thronghgthe line will'not result in mechanical failure of the bulb.

order of .010", at the'closed end portion '27, thereby to I make possible rapid response of the sensing element to I 7 :temperature changes, while at the base portion of the. y

I .bulb the wallthickness maybe on the orderof .012". :Within the closed portion 27there is disposed a thin in- .sulated sleeve of woven glass fibers 35 'imp'regnated'with a silicone compound, such sleeve having a thickness on the order of .003". Inside the sleeve 35 there is located a sensing element or coil 36 having terminal wires 37 and '38 connected respectively through suitable leads, indicated generally at 40, to connector or terminal pins 41 "mounted in glass bushings 43 and 44 carried by a supporting 'disc 45.

The slender tip portion 27 of the bulb 26 may have a nominal diameter on the order of 3 4 of an inch, the intermediate cylindrical portion 31 may have a diameter on the order of of an inch, and the cylindrical portion 28 --may have a diameter of /2 inch. In conjunction with .suchdiameters, the cylindrical portion 27 may be 1% inches in length, and the overall length of the bulb structure may be on the order of 3 7 inches.

Measuring from the juncture between the cylindrical portion 31 and .the tapered portion to the outer or flanged end ofthe bulb 26, the dimension may be 1 1 of an inch.

In forming the bulb 26 a very large number of drawing operations is preferably employed, without the use of annealing between the various drawing'steps. Instead,

,the amount ofdraw in succeeding steps is kept to a small ,value. develops a grain in a longitudinal direction which, we have found, results in a minimum number of microcracks per unit surface area. Preferably, the entire outside surface of the bulb 26 is perfectly smooth and free from By such procedure the bulb 26 work hardens and all burrs, blemishes, scratches and tool marks, and a microfinish may be obtained by the use of suitable compound wheels or the like. Where, as in the present instance, the. drawing procedure. is carried out without resorting to intermediate annealing steps, the resultant work-hardened material has a desirable toughness which .not only facilitates microfinishing of the surface, but also enhances the mechanical strength and resistance to 3 The wall thickness of the bulb 26 is preferably on the c I destructive vibratory forces. 'Wehave found that a bulb ,such as that shown in Figure 1 may be advantageously I formed, with such plurality of drawing operations, from 1 soft Monel metal of the deep-drawing, corrosion-resistant grade.' I

Also in conjunction with the bushing '23. there is 'pro-' 1 I vided a, connector'shell ,47'and a locking collar 48 surrounding the latter and adapted to secure the same to the bushing 23, said shell andcollar constituting part of the 1 fitting structure for supporting the bulb 26 and efiecting electrical connection thereto. s

As shown in-Figure 2, the bushing 23 has an hexagonal shouldered portion 50133! which a wrench may be applied to ,it'for'tightening and loosening the same, and against said shouldered portionan annular sealing ring 51' of 'silicone'cornposition may be disposed, for accommodation in an annular recess 52 in the boss'21. Further, an I I annular ring of silicone composition 52a may be provided I in :an internal annular recess 53 in the bushing 23; for i I engagement with the exterior wall of 'the'enlarged por- I tion 28 of thebulb'26 to provide a snug mounting for the *bulb' andto efiect a seal for all normal conditions ofpressure of the fluid in the line 20; Where line pressures exceed normal, the ring 52ainay' yield'to permit a controlledleakage- I I The connector shell 47 'has an externally threaded-end portion .42ada'pted. to accommodate the internally threaded, collar of a, cooperable female electrical fitting '(notshown) by which electrical connections; are: effected to the terminal pins 41.

' 'At its open end, the bulb 26 has an outturned flange: 54' F accommodated in'an enlarged bore ofaskirt portion 55 of the bushing 23, said enlarged bore terminating at an internal abutment shoulder engaged by a sealing washer,

as will now be explained; I Withinsaid skirt portion there is furtheraprovided an annular elasticsealingwasher 57,

engagingthefiange 54 of the bulb 26 and also engaging,

as seen in Fig. l, the internal abutment shoulder of the bushing 23 which is located above the washer 57 and is spaced above the flange 54. The washer 57 may con .stitute a tight seal, if such should'be desired, or it? may constitute a virtually non-sealing resilient element or member. The washer 57 is operable in conjunction with the locking and releasing action of the locking collar 48, as will now be further explained.

For the purpose of releasably mounting the bulb 26 in the bushing 23 and to facilitate quick release and/or locking of said bulb, the skirt 55 of the bushing 23 is provided with a pair of oppositely disposed bayonet slots 59 accommodating bayonet pins or projections 60, which latter are carried by the locking collar 48 and project radially outward therefrom along a diametric line.

The

i collar 48 slidably fits on the connector shell 47 and engages an outwardly extending flange 62 of said shell, as 'seen in' Figure 1, said collar being retained in place by a usual type of retaining ring 63 disposed in an annular groove in the shell.

For the purpose of easily and quickly manipulating the locking collar 48, as by turning the same to lock or release it, there is provided a pair of oppositely disposed, manually engageable lugs 65 having suflicient length to provide a secure finger grip.

With the above assemblage the resilient annulus 57 will be under compression as viewed in Figure l, and will retain the bayonet pins 60 in their locked positions in the slots 59. Upon the locking collar 48 being turned counterclockwise, as viewed in Figure 3, the annulus 57 will suffer a slight compression due to inward axial movement of the collar and the connector shell 47, and thereafter the collar and shell will become free, for removal from the bushing 23. I i

. If the sealingwasher 57 is made to l-lave a tight'fit about the enlarged portion 28 of the bulb 26, and if it contains suflicient mass to virtually completely fill the space existing between the flange 54 and the shouldered portion 50 a tight seal will be effected-between such parts when. the collar 48. is attached to the bushing 23. Or, as shown in Figure 1, the sealing washer 57 may have a lesser mass so as to not completely fill the space between the flange 54 and the shoulder portion 50, in which case a controlled leakage may occur past the sealing washer upon excessive pressures being encountered in the line 20.

It will now be understood that when the bulb 26 is suitably fastened to the connector shell 47 the assemblage of bulb, shell and locking collar 48 may be readily, quickly removed from the bushing 23 for replacement or servicing, as conditions require;

In accordance with the present invention the bulb 26 and shell 47 are so fabricated and joined as to present a minimum number of exposed cracks, crevices or pockets in which contaminating fluid may remain to cause injury to personnel servicing the equipment. In attaining this objective We effect a complete, annular sealing weld between the flange 54 of the bulb 26 and the connector shell 47, thereby to obtain an integral junction between these two components. Preferably the connector shell 47 is also formed of Monel metal, and to avoid introducing a different kind of metal by the welding procedure, whereby electrolytic action or corrosion might occur due to the radioactivity'or chemical composition of the contaminated fluid, the welding is accomplished by a projection technique, utilizing the material of the components themselves. In accomplishing this, see Figure 6, the flange 62 of the connector shell 47 is provided with an annular rib or bead 67, and the flanges 54 and 62 are brought together in a manner to cause the bead 67 to melt and to fuse the said flanges into a solid, integral unit. The welded joint is then turned down, finished and polished, whereby it is devoid of any cracks or crevices. Thus, the assemblage of bulb 26 and connector shell 47 becomes in effect a unitary piece formed entirely of a single metal alloy, in the present instance, Monel metal.

As already mentioned above, the threaded portion 42 of the connector shell 47 is adapted to accommodate the threaded fitting collar of a cooperable female electrical fitting (not shown) which also generally includes a cooperable shell.

For the purpose of keying the connector shell 47 to the mentioned cooperable shell (not shown), an internal projecting lug 70 is provided adjacent the outer lip portion or end of the shell. To avoid the making of any pockets in the outer end surface, beyond those absolutely necessary, the projecting lug 70 is formed as an integral part of the shell in the following manner: When the shell is initially fabricated, it is turned from solid bar stock, and an internal annular rib is formed, having a cross section similar to that of the lug 70. Thereafter, all but a small portion of the rib is broached away, leaving only the lug remaining. Thus, as distinguished from prior constructions where the keying lug is formed by lancing inwardly a finger from a wall portion, the present improved keying structure leaves the outside annular end surface of the connector shell entirely devoid of any pockets or recesses whereby it constitutes a perfectly flat sealing surface.

Fig. '4 illustrates a modified structure made in accordance with the invention. As shown in this figure, the connector shell 47 is devoid of any retaining means such as the retainer ring 63 shown in Fig. l, and instead the collar 48a is provided with a locking set screw 74 which may be tightened against the outside of the shell 47 to rigidlysecure the collar thereto. With this construction the collar 48a will be immovable on the connector shell 47 at all times that the set screw 74 remains pulled up tight. With the construction shown in Fig. 1, the collar 48 may be turnable with respect to the connector shell 47 at all times. The construction of Fig. 1 may be of advantage when applying the bulb 26, shell 47 and collar v48 to the bushing 23, since a somewhat greater freedom 6 of movement is had by the collar 48 during the seating of the bayonet pins 60 in the bayonet slots 59. I It will thus be seen from the above construction that we have provided an improved pyrometer bulb structure which has a maximum degree of strength while still re-v taining -a very rapid response characteristic. The bulb structure is so formed that it has a minimum number of cracks or crevices wherein a contaminating substance might become lodged, and by virtue of the welded construction there exists a minimum number of separate pieces, further making for maximum strength. By the use of Monel metal the effect of corrosive substances is reduced to a minimum, and through avoiding special brazing and soldering materials any electrolytic action is eliminated. By virtue of the double bayonet pin and slot construction making for ease of separation of the collar 48 and shell 47 from the bushing 23, replacement of the bulb may be readily, quickly effected. Also, by virtue of the fit of the elastic sealing washer 57 a controlled leakage of liquid may take place when excessive press sures are encountered in the pipe line, while at the same time a tight seal is possible for normal working pressures of the liquid.

Variations and modifications may be made within the scope of the claims, and portions of the improvements may be used without others.

We claim:

1. In combination, a pyrometer bulb structure for disposition in fluids contaminated with radioactivity, comprising an elongate tubular body closed at one end and open at the other end with an outturned flange at said other end, all portions of said body being integral with each other; a tubular connector shell adapted to coact with a cooperable electrical fitting, said shell having an inwardly disposed end and an outwardly disposed end, and containing electrical connector pins, the inwardly disposed end of the shell abutting the said open end of the bulb body, both said abutting ends being welded and fused together and constituting a junction devoid of cracks, said shell being externally threaded for accommodating a threaded fitting collar and the other end of the shell having an annular, perfectly flat sealing surface adapted to seal against a similar surface, said outwardly disposed end having an internal, inwardly extending projection formed integral therewith for keying purposes adjacent the said sealing surface, and the latter being continuous and unbroken; a mounting bushing adapted to receive and support said bulb body, said bushing having an internal annular abutment shoulder for positioning said body; a resilient sealing washer engaged with the said flange and annular abutment shoulder; and a turnable locking collar inseitable in said bushing and adapted to receive through it the said connector shell for securing the same in said bushing without requiring turning of the shell and body, said locking collar having a pair of oppositely disposed bayonet projections .and said bushing having a pair of cooperable bayonet slots for receiving said projections, thereby to establish a quick-acting locking and releasing connection between V the bushing on the one hand and the bulb body, shell and collar on the other hand.

2. In combination, a pyrometer bulb structure for disposition in fluids contaminated with radioactivity, com

prising an elongate tubular body closed at one end and.

open at the other end, all portions of said body being integral with each other; a tubular connector shell adapted to coact with a cooperable electrical fitting, said shell having an inwardly disposed end and an outwardly disposed end, and containing electrical connector pins, the inwardly disposed end of the shell abutting the said open end of the bulb body, both said abutting ends being welded and fused together and constituting a junction devoid of cracks, said shell being externally threaded for accommodating a threaded fitting collar and the outwardly disposed end of the shell having an annular, perfectly flat sealing surface adapted to seal against a similar surface, said outwardly disposed end having an internal, inwardly extending projection formed integral therewith for keying purposes, adjacent the saidsealing surface, and the latter 1" being 1: continuous and unbroken; a mounting bushing adapted to receive and support said bulb body, said bushing having an internal annular abutment shoulder for positioning said body; and a locking collar insertablein said bushing and adapted to receive through it the said connector shell for securing the same in said bushing, said locking collarhaving a pair of oppositely disposed bayone't projections and said bushing having a pair of cooperable bayonet slots for receiving said projections, thereby to establish a quick-acting locking and releasing connection between the bushing on the one hand and the bulb body, shell and collar on the other hand, said connector shell having an external shoulder engaging one end of the locking collar, 'and' having an" annular groove adjacent theother end of the collar; and a removable retaining ringiin said annular groove, providing an abutment for preventing removal of the collar from the shell.

3. In combination, a pyrometer bulb structure for disposition'inrfluids contaminated with radioactivity, comprising anelongate tubular body closed at one end and open at the other end, all portions of said body being integral with each other; a tubular connector shell having an inwardly disposed end and an outwardly disposed end,

and adapted to coact with a cooperable electrical fitting, 'said shell containing electrical connector pins, the inwardly disposed end of the shell abutting the said open end of the bulb body, both said abutting ends being welded and fused together and constituting a junction devoid of cracks, said shell being externally threaded for accommodating a threaded fitting collar and the other end of the shell having an annular, perfectly flat sealing surface adapted to seal against a similar surface, said outa t i v wardly disposed end having an, internal, inwardly extending projection formed integral therewith for keying pur poses adjacent the said sealing surface, and the latter being continuous and unbroken; a mounting bushing adapted to receive and support said bulb body, said bushing having an internal annular abutment shoulder for positioning said body; and a locking collar insertable in said bushing and adapted to receive through it the said connector shell for securing the same in said bushing, said locking collar having a pair of oppositely disposed bayonet projections and said bushing having a pair of cooperable bayonet slots for receiving said projections, thereby to establish a quick-acting locking and releasing connection between the bushing on the one hand and the bulb body, shell and collar on the other hand, said locking collar having a settscrew adapted to be tightened against the connector shell to prevent separation of said collar and shell;

4. The invention as defined in claim 3 in which the bulb body, connector shell, bushing, locking collar and welded junction between the shell and bulb body are constituted of non-corrosive Monel metal.

References Cited in the file of this patent I UNITED STATES PATENTS 1,478,821 Foster Dec. 25, 1923 1,660,504 Grubb Feb. 28, 1928 2,271,975 Hall u- Feb. 3, 1942 2,476,099 Knudsen July 12, 1949 1 OTHER REFERENCES Brown Instrument Company Catalog 1102 (p. 1937. (Photostat available in Division 56.)

Brown Pyrometer Catalog 15D (p. 33), 1937. (Photostat available in Division 56.) 

